1. Technical Field
The present invention relates to a flexural vibration piece, a flexural vibrator, and an electronic device.
2. Related Art
To date, it has been known that when a flexural vibration piece is downsized, the Q value decreases, and the vibration is inhibited.
To describe in detail, a flexural vibration piece is such that a temperature difference occurs inside due to the temperature of a compressing surface rising and the temperature of a stretching surface dropping accompanying an elastic deformation due to a flexural vibration. Because of this, a vibration called a thermal relaxation vibration, inversely proportional to a time needed (a relaxation time) until the temperature difference is eliminated (a temperature equilibration condition is attained) by heat conduction (heat transfer), occurs in the flexural vibration piece.
When downsizing the flexural vibration piece, the frequency of the thermal relaxation vibration and the frequency of the original flexural vibration come closer, meaning that a phenomenon occurs wherein the Q value decreases, and the original flexural vibration is inhibited. This phenomenon being called a thermoelastic loss, a thermoelastic effect, or the like, as an improvement measure, Laid-open Japanese Utility Model Publication No. 2-32229 attempts to suppress the decrease in the Q value caused by thermoelastic loss by forming a groove or a through hole in a rectangular cross-section of the flexural vibration piece, increasing the distance of a conduction path of a heat transfer from the compressing surface to the stretching surface, and causing the frequency of the flexural vibration and the frequency of the thermal relaxation vibration to diverge.
However, the flexural vibration piece is such that, when forming a through hole in a vibrating portion (hereafter referred to as a vibrating arm portion) as in Laid-open Japanese Utility Model Publication No. 2-32229, there is a problem in that the rigidity of the vibrating arm portion decreases markedly. Also, the flexural vibration piece is such that, even when providing grooves (hereafter referred to as groove portions) with an H type cross-sectional shape in the vibrating arm portion, as in Laid-open Japanese Utility Model Publication No. 2-32229, the suppressing of the heat transfer from the compressing surface to the stretching surface is insufficient, meaning that there is room for improvement in the suppressing of the decrease in the Q value caused by thermoelastic loss.